1. Field of the Invention
The present invention relates to a signal outputting method of outputting an electric signal generated in an envelope constructing a cathode ray tube to the outside of the envelope, a method of mounting a signal outputting electrode for outputting the electric signal to the outside of the envelope, and a cathode ray tube having the function of outputting the electric signal to the outside of the envelope.
2. Description of the Related Art
In an image display apparatus such as a television receiver or a monitor for a computer, for example, a cathode ray tube (CRT) is widely used. In the CRT (hereinbelow, also simply called a xe2x80x9ctubexe2x80x9d), an electron beam is emitted from an electron gun provided therein onto a fluorescent screen and an image is formed according to a scan with the electron beam. The CRT generally comprises a panel in which a fluorescent screen is formed and a funnel provided integrally with the panel. In the rear part of the funnel of the CRT, an elongated neck having therein an electron gun is formed. The inner surface from the neck to the fluorescent screen of the panel is covered with an inner conductive film, electrically connected to the anode, and is maintained at a high voltage. The external view of the CRT as a whole is a funnel shape formed by the panel, funnel, and neck. In the following description, the whole portion of the CRT formed by the panel and the funnel will be also called an xe2x80x9cenvelopexe2x80x9d.
In the CRT, there is a case such that an electric signal generated in the tube (that is, in the envelope) is desired to be outputted to the outside of the CRT (that is, the outside of the envelope which will be also simply called xe2x80x9coutside of the tubexe2x80x9d). For example, the applicant of the invention has disclosed a CRT in Japanese Patent Application No. 11-72658 in which detecting means for generating a detection signal according to an incident electron beam is provided in an overscan area of an electron beam in the tube. According to the invention, a detection signal generated by the detecting means in the tube is outputted to the outside of the tube and is used, for example, for controlling the scan position of an electron beam. In the invention, for example, by mounting signal outputting electrodes directly on the inner and outer walls of the envelope so as to face each other, a capacitor using a part of the envelope as a dielectric is formed. By electrically connecting the electron beam detecting means to the capacitor, the detection signal generated by the detecting means is outputted to the outside of the envelope. The electrode mounted on the inner wall of the envelope is insulated from an inner conductive film formed in the tube.
On the other hand, the manufacturing process of the CRT includes a so-called gettering process for introducing a substance such as an active metal called a getter (for example, barium) into the tube so that unnecessary gases are absorbed by the getter, thereby maintaining a high vacuum state in the tube. In the method of mounting the signal outputting electrode, however, it is feared that the getter introduced in the gettering process is adhered to the periphery of the electrode mounted on the inner wall of the envelope and the signal outputting electrode and the inner conductive film formed in the tube are made conductive. When the inner conductive film and the signal outputting electrode are made conductive, there is the possibility that the detection signal generated in the envelope cannot be accurately outputted to the outside. It is therefore desirable to mount the electrode in consideration of the gettering process.
The invention has been achieved in consideration of the problem and a first object of the invention is to provide a signal outputting electrode mounting method capable of mounting a signal outputting electrode for outputting an electric signal generated in an envelope of a cathode ray tube to the outside without being adversely influenced by a getter.
A second object of the invention is to provide a method of outputting a signal in a cathode ray tube and a cathode ray tube, which can excellently outputting an electric signal generated in the envelope of the cathode ray tube to the outside of the tube without being adversely influenced by a getter.
According to a method of mounting a signal outputting electrode in a cathode ray tube of the invention, a signal outputting electrode for outputting an electric signal generated in an envelope of the cathode ray tube to the outside of the envelope is mounted onto an inner wall of the envelope in a state where at least the periphery of the signal outputting electrode is apart from the inner wall of the envelope.
According to a signal outputting method in a cathode ray tube of the invention, a signal outputting electrode for outputting an electric signal generated in an envelope of the cathode ray tube is mounted onto an inner wall of the envelope in a state where at least the periphery of the electrode is apart from the inner wall of the envelope, and the electric signal generated in the envelope is outputted to the outside of the envelope via the signal outputting electrode mounted on the inner wall of the envelope.
A cathode ray tube according to the invention comprises: an envelope; a light emitting portion for emitting light in accordance with a scan with an electron beam emitted in the envelope; and a signal outputting electrode which is mounted on an inner wall of the envelope in such a manner that at least the periphery is apart from the inner wall of the envelope and which outputs an electric signal generated in the envelope to the outside of the envelope.
According to a method of mounting a signal outputting electrode of the invention, a signal outputting electrode is mounted onto an inner wall of an envelope in a state where at least the periphery of the electrode is apart from the inner wall of the envelope.
According to the signal outputting method and the cathode ray tube in the invention, an electric signal generated in an envelope is outputted to the outside of the envelope via a signal outputting electrode mounted in a state where at least the periphery of the electrode is apart from the inner wall of the envelope.
Others and further objects, features and advantages of the invention will appear more fully from the following description.